This invention relates generally to radiation apparatuses and methods, and in particular to devices for supporting or positioning patients in prone positions for radiotherapy, imaging and/or treatment simulation.
Breast cancer is one of the most common cancers among women in the United States. Each year, about 200,000 American women are diagnosed to have breast cancer. One of eight women born today will be diagnosed with breast cancer at some time during their lifetime. Depending on the type, stage of the cancer and other factors, patients with breast cancer can be treated with radiation therapy, surgery, and other forms of therapy. Radiation therapy in the breast is usually used in conjunction with surgery and may also be combined with chemotherapy. Most patients receive whole-breast irradiation (WBI) therapy after lumpectomy (surgical removal of cancer lumps) to destroy cancerous cells that may remain in the area after lumpectomy. Some patients opt for accelerated partial-breast irradiation (PBI) therapy because of the appealing shorter treatment time.
The vast majority of radiation therapy of breast cancer is carried out with the patient in a supine position due to the ease of access and patient comfort. In this position however, gravity depresses the breast towards the patient's torso and the breast tends to spread laterally over the chest wall. This makes accurate positioning of the breast difficult and complicates the location of internal structures relative to the radiation beam directions required to deliver the prescribed dose to the breast. Treatment planning options are constrained by the greater proximity of the breast to the chest wall and critical organs including the lung and heart. Also, due to the flattened shape of the breast in a supine position, use of devices such as wedge filters, beam spoilers bolus etc. are often required to overcome non-homogeneous dose distribution and skin overdose.
In some situations it is believed desirable for radiation treatment to be carried out with the patient in a prone position so that gravity pulls the breast away from the chest wall. Prone patient set up may minimize radiation doses to the chest wall and critical organs including the heart and lungs, and provide more uniform dose delivery. In addition a prone position results in less motion of the breast caused by respiration.
Conventional supporting devices for prone breast radiotherapy consist of raised platforms or cushions that rest on top of a couch top, which allow the treated breast to hang into the space between the platform or cushion and the couch top. FIG. 6 illustrates a conventional radiation treatment table for prone breast radiotherapy. With these designs, the upper thorax, arms and head are supported by the platform which in turn rests on the couch top below the breast. A raised platform or cushion placed onto a conventional couch top significantly limits the physical clearance for rotating a radiotherapy treatment machine around the patient as required to direct the treatment beam from various directions. Physical and visual access to the breast being treated is also restricted by the presence of the conventional couch top below the breast.